Tom Veatch
08-10-2009, 7:25 PM
In another venue, there's been a long discussion, filled with confusion, about miter gauges, angles, and settings. Just to satisfy my own curiosity I have a couple of questions for the inhabitants of SMC.
First question:
On your tools (RAS, Miter Saws, etc.) and miter gauges, to get a square crosscut at 90° to the edge of the part, do you set the angle on the tool or gauge to 0° or 90°?
I must confess that I don't recall ever seeing any woodworking tool that uses a 90° index mark for a square crosscut. There certainly may be some, but in my experience, it's always been "set the gauge to the complement of half the included angle of the joint" (90°-angle/2). For example, 0° for a square cut (180° joint), 45° for a 90° joint, 22.5° for an octagon (135° joint), 30° for a hexagon (120° joint), etc.
Of course, that's assuming the joined pieces have the same width.
Second question:
What's the definition of "miter angle"? I may be swimming upstream, but to me, the "miter angle" has always meant the setting on the miter gauge to achieve the angle needed for the cut. The opposing view is that the "miter angle" is half the included angle of the joint. Both definitions yield the same result for a 90° joint (45°) but yield complements of each other for any other joint angle (yeah, I know, 45° is its own complement).
I guess it all started with a discussion of trimming out a corner where the walls joined at 91°. Is the miter angle 44.5° or 45.5°? I'd set my miter gauge/saw to 44.5° which, in my mind, is the "miter angle". Half the included angle is 45.5°
First question:
On your tools (RAS, Miter Saws, etc.) and miter gauges, to get a square crosscut at 90° to the edge of the part, do you set the angle on the tool or gauge to 0° or 90°?
I must confess that I don't recall ever seeing any woodworking tool that uses a 90° index mark for a square crosscut. There certainly may be some, but in my experience, it's always been "set the gauge to the complement of half the included angle of the joint" (90°-angle/2). For example, 0° for a square cut (180° joint), 45° for a 90° joint, 22.5° for an octagon (135° joint), 30° for a hexagon (120° joint), etc.
Of course, that's assuming the joined pieces have the same width.
Second question:
What's the definition of "miter angle"? I may be swimming upstream, but to me, the "miter angle" has always meant the setting on the miter gauge to achieve the angle needed for the cut. The opposing view is that the "miter angle" is half the included angle of the joint. Both definitions yield the same result for a 90° joint (45°) but yield complements of each other for any other joint angle (yeah, I know, 45° is its own complement).
I guess it all started with a discussion of trimming out a corner where the walls joined at 91°. Is the miter angle 44.5° or 45.5°? I'd set my miter gauge/saw to 44.5° which, in my mind, is the "miter angle". Half the included angle is 45.5°